I love Mark Crosbie’s cool drum sequencer, which scans a “card” of bricks to form the beat.

SoundMachine is an interactive music tool to collaboratively develop music. SoundMachine scans 2×2 colour LEGO bricks arranged in 4 tracks of 8 beats. The colour information is converted to MIDI messages by a Processing sketch, which sends MIDI to Ableton Live to play the instruments.